Final answer:
The first Whataburger drive-thru was installed by franchisee Jack K. Fields in 1971, marking a pivotal moment in convenience for the fast-food industry.
Step-by-step explanation:
The first Whataburger drive-thru was installed in 1971 by franchisee Jack K. Fields. This addition was an innovation in the service model of the fast-food industry, helping Whataburger expand its customer base by offering a more convenient eating option. The drive-thru service has since become a staple in fast-food chains worldwide, significantly shaping the industry. The answer to the question is B) Jack K. Fields. It was Jack K. Fields, an early Whataburger franchisee, who installed the first drive-thru at a Whataburger location in 1971. This innovation allowed customers to order and pick up their food without leaving their vehicles, revolutionizing the fast-food industry.